 The efficacy was about 30% in infants 6 to 12 weeks of age and about 50% in infants 5 to 17 months of age in the first year of the trial.The RTS,S vaccine was engineered using a fusion hepatitis B surface protein containing epitopes of the outer protein of "Plasmodium falciparum" malaria sporozite, which is produced in yeast cells.It also contains a chemical adjuvant to boost the immune system response.